At current time, the mobile phones are being developed mainly at two directions, one is voice-oriented and the other one is smart-phone. Smart-phones are equipped with powerful processing capability besides the telephone function, and it is similar to a microcomputer, which integrates many functions such as communication, Personal Digital Assistant (PDA) and entertainment.
In order to display a lot of information, the smart-phone requires a large screen, and this is one reason that quite often a smart-phone would discard the keypad and uses a touch screen instead. In this way, not only the space on the smart-phone is saved, but also the smart-phone can have diversified interface. For common mobile phones that designed for finger touch sensing, the virtual keypads on the screen need to be enlarged to obtain larger touch area, so as to reduce the mis-touch rate. As a result, the screen size also needs to be enlarged, and the dimension of the whole mobile phone is more than 20-30%, or even 50% larger than other mobile phones. It will be difficult to carry away a large mobile phone as well as hard to use it by single hand.